Traffic control apparatus



y 1941- J. L. BARKER 2,243,187 TRAFFIC CONTROL APPARATUS Filed May 31, 1939 REST PM! 76 A 6x651! 36 HI n M851: B AMBER INVENTOR. J00 L. BARKER A TTORNE Y Patented May 27, 1941 UNITED STATES PATENT OFFEQE 2,243,187 TRAFFIC CONTROL APPARATUS Application- May 31, 1939, Serial No; 276,499 I 19 Claims.

This invention relates generally to road traific control apparatus for the control of right of way traific signals at intersections of traffic lanes, streets and highways. There are two general types of such control, one commonly classified as fixed time control and the other as traflic actuated control. In the case of the fixed time control the usual traffic signals such as green, amber and red lights ordinarily provided for each street are operated by a timing mechanism through a predetermined cycle which is continuously repeated whether there is trafi'ic present or not, the cycle including alternate green signal periods for the intersecting streets for example, with a red signal displayed to one street during the green signal period of the other street, and with one or both amber signals displayed at each change from green to red.

In the traiiic actuated type of control, instead of continuously repeating the display of the green, amber and red signals, the control mechanism or controller normally rests with the go signal displayed to one street and the stop signal displayed in the other. One or more traflic detectors in the form of vehicle actuated devices or 17?. pedestrian actuated pushbuttons are located in the street to which the stop signal is displayed when the controller mechanism is at rest. "An actuation of one of these detectors will cause the I controller to start up and go through a cycle of t operations during which the go signal is displayed alternately to the two streets and after which the controller will again come to rest with the stop signal displayed in the street wherein the detectors are located and with the go signal displayed in the other street.

Both of these types of traffic control are well known in the art. The purpose of this invention is to provide an apparatus by which a traffic controller of the first type which normally operates continuously can readily be converted into one of the second or trafiic actuated type. It is arranged to do this with a minimum of change in the fixed time timer which is to be so converted.

A fixed time traffic controller usually consists essentially of a camshaft bearing cams which make and break electrical circuits controlling red, green and amber signals on the two streets. This camshaft is driven by a motor. By the use of so the adaptor apparatus disclosedherein such a fixed time controller can be converted into a tramc actuated controller without changing any of the internal circuits of the fixed time controller except the'motor circuit'which is ordi- 53 itself.

narily easily segregated from the signal circuits for external control connection.

In converting a fixed time control system to a trafiic actuated control system some traffio detector means must first beprovided to determine the presence of traific on one of the intersecting streets, usually the side street at an intersection with a main highway. Such a detector may be a pushbutton, which may be operated by pedestrians, or may be an electrical contact device set into the roadway to be operated by vehicle wheels, or may be a magnetic or sound actuated or energy beam actuated device which operates an electrical contact from the magnetic infiuence or sound of passing Vehicles or from the interruption of an energy beam by passing vehicles, for example. Various forms of these devices are already well known in the art.

Having provided some tramc detector means, the principal differences between a fixed time controller as discussed above and a simple form of traffic actuated controller are essentially two. First,'the timing motor of the controller must be interrupted, preferably at the end of the highway green period,'in the absence of cross street traffic detector actuation, and must be energized again upon cross street detector actuation; and second, any detector actuation occurring in the cross street amber or highway green periods must be stored until after the end of the highway green period so that such actuation will thereby maintainthe motor energized at the end of the highway green period and cause another signal cycle to provide a cross street green signal period for Thus for this second difference some latching device such as a lock-in relay for example must be provided, and such relay when once energized by a momentary traffic detector actuation at any time except in the cross street 0 green period must be locked-in or maintained energized until the next cross street green period. In accordance with the present invention an adaptor apparatus is provided to add the features required to overcome these difierences discussed above and thereby adapt or convert a fixed time signal controller to a traflic actuated type.

In the arrangement disclosed herein the adaptor apparatus is interposed between the signals and fixed time controller cam contacts normally controlling the signals. The adaptor apparatus comprises essentially a set of relays operated by the normal signal output current of the fixed time controller, the relays in turn operating the signals. The adaptor is arranged so that its output signal cycle can be varied from the of causing the trafiic signals to operate on anyone of several cycles without the necessity for changing the output cycle of the fixed time con-' vide an apparatus of the type described which i is capable of receiving any one of several signal cycles from a fixed time controller and of caus-' ing the signals to operate either on the cycle received from the fixed time timer or upon some other cycle. I

It is a further object of this invention to provide an adaptor of the type described in which momentary interruptions of the output current of the fixed time controller due to such causes as faulty contacts or irregular cam surfaces will not interrupt the signal normally accorded to traflic by the adaptor.

It is also an object of this invention to provide an adaptor of the type described which can be operated by the signal currents of a fixed time controller without the necessity for rearranging any of the circuits within the fixed time controller other than the motor circuit which can be easily segregated.

A better understanding of this invention can he had by referring to the drawing. At either side of the drawing will be seen the power supply wires, which ordinarily supply alternating current but which are identified as positive and negative for convenience of reference. In the upper left corner is shown. a fixed time cycle controller consisting of a camshaft S with cams .CI to C1 inclusive operated by the motor M. This camshaft is shown diagonally with respect to the corners of the drawing. Directly below the camshaft are two relays numbered respectively 6 and l which constitute part of the adaptor. These relays are operated by the opening and closing of cam contacts pairs 9, l0, H, l2, I3, I 1 and 15, one contact of each pair being connected directly to the positive power wire.

In the lower center of the drawing is a relay numbered 8 which is also part of the'adaptor. This relay is controlled cooperatively by the traffic detectors 23 shown in B street at the street intersection in the lower right part pf the drawing and byrelays 6 and T. The three relays fi, 1 and 8 cooperate to control the traff c signals shown in the lower right part of the drawing as disposed along'two intersecting streets A and B.

The tralfiic detectors 23 can be set in the roadway as shown or they could be of the pushbutton type and be mounted adjacent to the roadway for the use of pedestrians. Detectors of both types are often used so'that vehicular trafiic and pedestrians can operate the signals. In the 'lower leftcorner of the drawing is a transformer T'which is preferably used to provide a source of low voltage for traflic detectors and to provide proper voltage 'for" operating relays 6 and "I in series with the condensers 33 and 22.

The adaptor comprises relays 6, l and 3 with their several armatures and contacts, transformer T and condensers 22 and 33 as well as the associated circuits connecting these parts to each other and to the signals and to the fixed time controller.

The arrangement of cams shown on shaft S of the fixed time controller could be used to give various signal sequences were the signals to be connected directly thereto. Cam Cl could be used to provide two amber periods per cycle common to both streets. Cams C2 and C3 would provide'alternate red and green signal indications lasting one half of a cycle each. Cams C4 and C5 would give slightly shorter alternate red and green signal indications not overlapping theamber periods. Cams C6 and C1 would give one independent amber period per cycle for each street.

Switches l9 and 32 permit connecting the coil 'of relay 6 to the half cycle cam contacts Ill and I! or the shorter period cam contacts 12 and I3. Switches I6, 69 and 13 permit connecting the coil of relay 1 directly to amber cam contacts l4 and I 5 or to the common amber cam contact 9 through armature 63 of relay 6. Switches 11 and I8 permit connecting the coil of relay 1 to the short period cam contacts l2 and I3. By properly setting these various switches any of several standard output cycles of a fixed time controller can be selected as the input cycle of the adaptor. The adaptor will operate similarly on any of these cycles as will be further described below.

The chart in the upper right corner indicates the periods during which the several cam contacts 'are closed. The heavy line on the same level with each cam indicates that portion of the cycle during which the contact is closedand the light line on the same level indicates the "position of the cycle during which the contact is open. Thus in the top line the closure of 1 of the chart.

contact 9 during both of the change periods is indicated by the heavy lines in periods 2 and 4 Similarly the second level of the chart indicates that contact I0, associated with cam C2, is closed during the time indicated by periods and 2, i. e, during one of the green periods and the subsequent change period of the fixed time controller. Contact 10 is open during the timeindicated by periods 3 and 4. The next succeeding five lines below indicate the portion of the cycle of the fixed time controller during which contacts II, l2, l3, l4 and. I5 are closed.

-The, line in the chart numbered 60 indicates when relay 6 is energized, the energizedperiod heingindicated by the dark line. Similarly line 10, the bottom line on the chart, indicates when relay I is .energized. RelaysB and 1 will operate indicate the parts of the cycle during which the named signal would be energized. Switches 48,

52, 5$,"6 f and 65 are u'sed'to control th e' 'output signer sequenceof the adaptor; L

By setting" theseswitches the A green signal can be caused to remain energized during" the A amber period or the B green signal can 'be caused to remain energized during the B amber period. Similarly the amber signal in either street can be made to follow the green period only or to follow both the green period and the red period. The red period can be caused to coincide with the green period in the opposing street or it can be extended into the amber period thereof. Thus any of the standard traflic signal cycles can be obtained by the proper setting of these switches. Their use for this purpose will be explained in detail below.

As shown in the drawing the apparatus is at rest with the timer motor M deenergized and the camshaft S consequently not revolving. Relay 6 is deenergized. Relay I is energized having been operated through the circuit starting at positive power thence through cam contact l5 and switch 13 to the coil of relay 1, thence through condenser 22 to negative power at 61. A parallel circuit is also established feeding power to the right side of the coil of relay 1 through armature 2| of relay 1 and wire 20.

The green signal on A street designated as AG is energized through the circuit starting at positive power thence through switch 18, armature 40 of relay 6, wire 4|,.armature 42 of relay 8, through its upper contact into wire 43 and switch 65 to the signal AC thence through wire 59 to negative power. The B street red signal, designated BR, is energized through the circuit starting at positive power, switch 18, armature 40 of relay 5, wire 64 thence upward into switch 48 and through wire 49 into the signal BR thence through wire 58 to negative power. No other signals are energized.

A vehicle operating either detector 23 on B street will feed negative power into the coil of relay 8 through wire 24. From the other terminal of relay 8, the circuit goes through armature 25 to coil 26 of transformer T thence to ground. Coil 26 provides a low voltage suitable for operating relay 8 through the detector 23. Relay 8 will thereupon operate and hold itself in the operated position through its armature 28 which bypasses the detectors and supplies negative power to the right side of its coil. Relay 8 will then remain operated until both armatures 25 and 62 are simultaneously open which condition will occur later when the green signal is given to B street.

The energization of relay 8 does three things.

(1) It starts the motor M through armature 39 which completes a circuit directly from positive power via wire 15 through the coil 29 of motor M to negative power.

(2) It deenergizes the A street green signal AG through opening the circuit previously traced to this signal at armature 42 of relay 8.

(3) It energizes the A street amber signal AY through the circuit starting at plus power, switch '58, armature 4i] thence via wire 64 to armature 45, then through the upper contact thereof to armature 44 which feeds into wire 41 connected to the A street amber signal AY then through wire 59 to negative power.

Camshaft S of the fixed time control is now revolving in the direction indicated by the arrow above its driving disc. In the connection shown in the drawing cam contact 9 associated with cam Cl can be neglected inasmuch as switch I6 is open. At the end of the A street amber period several changes will take place in the circuits associated with the cams substantially simultaneously.

Cam will open contact l and cam C5 will close contact l3. This will have no immediate effect on the apparatus inasmuch as relay 1 is already energized through the bypass circuit including itsown armature 2| as previously mentioned.

Also at this time cam C2 will open contact l9 and cam C3 will close contact II. The effect of this is to remove positive power from the left side of the coil of relay 6 and to connect positive power to the right side of the coil of relay 6 through switch 32. Relay 6 will thereby be energized through the circuit from positive power thereof engages its contact and supplies positive power through wire 31 to the coil 29 of motor M thereby assuring that motor M will continue to be energized independently of the circuit through armature 3|! previously described. Relay 8 will now be deenergized by the separation of armature from its contact thereby opening the power supply tothe left side of the coil of relay 8. Actuation of the detectors 23 are of no effect during the B street green signal period because armature 25 and armature 62 are both disengaged from their contacts thus opening the circuit to the left coil terminal of relay 8. During all other parts of the signal cycle either one or both of these armatures will be engaging its contact thus making relay 8 responsive to actuations of detector 23.

. Armature 49 of relay 6 disengages from its lower contact thereby opening the previously described circuit feeding the A street amber signal AY. This last circuit is also opened at armature 44 of relay 8 shortly thereafter. As armature engages its upper contact it supplies positive power through wires 50 and 5|, switch 52 to the A street red signal AR thence to wire 59 to negative power. Also armature 49 establishes through its upper contact a circuit from positive power through wire 51!, armature 54, wire 55 and .switch 56 to the B street green signal BG thence through wire 58 to negative power. The signal indications have now changed :to accord the right of way to B street.

The camshaft S continues to revolve, timing the B street green signal period. At the end of the B street green period cam C6 will close contact l4 and feed positive power through switch 69 and resistor 39 into the left side of thecoil ofrelay 1. This will cause relay 7 to become deenergized since the right side of the coil is also connected to positive power and resistor 39 ha a relatively low resistance.

Armature 2| of relay 1 will thereupon drop into its lower position opening the positive power bypass circuit previously traced to the right side of the relay 1 coil. As armature 2| engages its lower contact it provides an additional source of positive power to coil 29 of motor M so that this motor shall remain running throughout the cycle despite changes which may occur in its other feed circuits. engages from its upper contact thereby extinguishing the B street green signal, the circuit for which was previously traced over wire 55' As Armature 54 of relay 1 also distiv'e power.

thereby providing an additional auxiliary circuit this armature engages its lower contact it' energizesthe B street amber signal BY through wire I ArmatureBZ of relay 1 engages its contact thus providing a circuit to the left coil terminal of relay 8. Relay 8 will now be energized by the 'next actuation of either detector 23 if any. The camshaft of the fixed time control contact removing the bypass positive power feed circuit'to the'right side of relay 5.

' Armature 36 also now disengages from its contact but this is of no immediate eifect since positive power is fed to thecoil 29 of motor M through the bottom contact of armature 2|.

Armature 40 disengages from its upper contact thereby extinguishing the B street amber signal thecircuit for which was previously traced. As armature 49 engages its-lower contact it ener- -gi'zes the '3 street red signal through wire 64, switch-48; wire 49, signal BR and wire 58 to negative power. energizes the A street greensignal AG through imultaneously armature 48 wire 64, armature 45 and wire 43 and switch '65 thence through signal AG and wire 59 tonega- Armature 25 engages its contact to the left coil terminal of relay 8.

The camshaft S of the controller continues to revolve, timing the normal A street green signal period, energy to motor coil 29 being fed through armature 2| of relay 1 and its lower contact. When thenormal A street green period has expired cam C1 closes contact l thereby supplying positive power to the right side of the coil of relay 1 through switch 13. Inasmuch as both cams C4 and C6 are disengaged from their respectivecontacts l2 and I4 no positive power is fed to the left side of the coil of relay 1. Thereforerelay I will be energized through its circuit previously described and will operate to raise its several armatures. Armature -2| will thereupon engage its upper contact and supply a bypass path for positive power to the right side of the coil of relay-1. As armature 2| disengages from its lower contact the motor coil 29 becomes deenergized since armatures 30 and 36 are also disengaged from their contacts, assuming that no further detector actuation has occurred to'energize relay 8. Armature 54 disengages from its lower contact and engages its upper contact but this has no immediate effect on the system inasmuch as no positive power is being fed to arma-. ture 54 at this time due to the factthat armature 40 is not engaged with its upper contact. Armature 45 disengages from its lower contact thus interrupting one circuit which feeds the A street green signal over wire 43. However, the A street green signal does not go out at this time since it is fed through a bypass-circuit inclu-ding armature 40, wire 4| and armature 42 of relay 8 over wire 43. The fact that armature 45 engages its upper contact is of no effect because armature 44 of relay 8 is not engaged with its contact. The apparatus, having timed the normal A street green signal-period, has now returned to its rest position with the-A-street green 7 and-theB street red signals remaining energized.

holding contact .Had there been an actuation of either detector 23 during the B street amber period or the normalA street green period relay 8"wou1d have been energized and locked in the energized position through its own armature 28. Had this ieration of relay 1 would have extinguished the A street green signal AG through the separation of-armature 45 from its lower contact because the bypass circuit previously described through wire 4| and armature 42 of relay 8 would'have also been open. Furthermore with relay 8 operated the contact of armature 45 with its upper contact would have energized the A street amber signal AY through its usual circuit inasmuch as armature 44 of relay 8 would be engaged with its contact. Hence we see that'if there had been an actuation during the preceding B street amber period or the normal A street green period the apparatus; insteadof coming to rest at the end of the normal A street green period with the A street green signal and the B street red signal energized; would have continued and started a new cycle which would be'the same asthat previously described.

Cam C5 may affect the operation of relay 1 during the first cycle after the signals are turned on.- Its'contact I3 is connected through switch |8 into the supply circuit for the coil of relay 1 in parallelwith cam contact |5. It operates as follows. Assume that when the controller was last turned on relay 1 wasenergized but cam C1 had opened contact I5. When the control is turned on again contact l5 being open and the circuit through armature 2| having been opened when the control was turned ofi, relay 1 will depend 'for its immediate energization on the closure of contact |3.- The fact that cam C5 is l3 closed insures the proper functioning of the signals during the first cycle after they are turned on.

The adaptor can be used with a fixed time control which has only one amber signal circuit. This condition can be simulated by closing switch l6 and opening switches 69 and". With this connection the control of relay 1 is transferred from cams C6 and C1 to cam C| operatingin conjunction with relay 6 but relay i operates just as it did when controlled by cams C6 and C1.- This is accomplishedas'follows. Withrelay 6 deenergized as shown'in the drawing one side of cam CI- by engaging contact 9 will energize relay 1 through the circuit including switch "3, armature 63, the lower contact associated therewith and wire 20 thus'putting positive power on to the right side of the coil of relay 1 which operatesit just as if cam C'l had closed contact '|5. Whenthe opposite side of cam Cl engages contact 9 relay 6 will have been energized by I 'camC3at contact -||.in accordance with-the previous explanation and plus power will be sent through armature 63 thereof into its upper contact which leads via wire H through resistance 39 tothe left side of the coil of relay 1 thereby deenergizing relay 1 just as if cam C5 had closed contact |4.- This arrangement makes the 5 A--fixed time controller with only onea'mber signal circuit is likely to be of the type giving a red signal impulse which does not extend into the amber period onthe other street;

Operation of the adaptor by such a controller can be simulated by closing switch It and opening switches 69 and 13 (as in th preceding paragraph), opening switches l1 and I8 and moving switches l9 and 32 into their right hand position. With this connection the control of relay 1 is as described in the preceding paragraph and the control of relay 6 is transferred from cam contacts [9 and H to earn contacts l2 and I3. The latter two contacts close at the same time as the former two but they open earlier in order to give a signal period not extending into the amber period. However, since relay 6 is operated by the closure of its control contacts, one to energize and the other to deenergize, the fact that cam contacts l2 and I3 do not remain closed for as long a period as contacts iil and I I, does not alter the cycle of operation of relay 6. Hence, as stated, the adaptor can he operated by a fixed time controller having only an amber signal circuit and in which the red signal impulse does not extend over into the amber period on the other street.

The fact that relays 6 and 'l are so connected that positive power must be connected to their left coil terminals to deenergize them is an important practical feature in that it permits successful operation of the adaptor by a fixed time controller in which th cams are not perfectly adjusted or cam overlaps or gaps occur.

The condenser 33 is used in series with the coil of relay 6 in order to permit connecting positive power to the left side of the coil of relay 6 without incurring a short circuit. Condenser 22 is similarly used in connection with the coil of relay 1. Resistors could be used instead of condensers 33 and 22 but the consequent loss of energy makes the condensers preferable.

The apparatus of the drawing with the signal control switches as shown will, as has been previously stated, give the following signal se- Periodl Period2 Period3 Periods Periodl StreetA Grcen Amber" Red Red Green. StreetB Red... Red Green." Amben. Red.

This cycle can be altered by changing the positions of any of the switches 48, 52, 56, 61 or 65. For instance, with switch 56 as shown in the drawing, the B street green signal is deenergized when the B street amber signal is energized. By moving switch 55 to its upper position, the B street green signal will remain energized during the B street amber signal period. This is due to the fact that the control of the B street green signal will now depend solely on armature 4B of relay 6 which engages its upper contact during the B street green and amber periods 3 and 4 as shown in the right hand corner of the drawing.

The B street red signal as shown in the drawing is connected so that it will be energized at the same time as the A street green signal and will remain energized during the A street amber period. However with switch :8 moved to its lower position the B street red signal would not be energized during the A street amber period since its circuit would be interrupted by the separation of armature 45 from its lower contact during the A street amber period. The separation be connected so that it will be energized during of armature 45 from its lower contact, however, will not deenergize the phase B red signal so long as there is no call registered by the operation of relay 8 since the bypass circuit throughwire 4| and armature 42 of relay 8 will be effective to keep the phase B red signal energized.

By moving switch 52 from its shown position to its lower position the A street red signal can the B street green signal period but extinguished during the B street amber period. The A street green signal can be caused to remain energized during the A street amber period by moving switch 65 to its lower positon. This is evident may be connected together so that when either one of them is energized both will be energized thereby giving a common amber period.

By using different combinations of switch positions any one of the standard signal sequences can be obtained. For example, to obtain the following sequence,

Periodl Period2 Period3 Period4 Periodl ,Street A; Green Amber. Red AmbeL. Green. StreetB Red... o Green... do. Red.-

the switches would be set as follows. 7 Switch 5'6 would be left as shown in the drawing thus giving the short green period on B street not running into the amber period. Switch 48 would be changed to the lower position so that the B street red signal would be out during the amber periods. Switch 65 would be left as shown in the drawing inasmuch as this connection gives the green which goes out when the amber comes on. Switch 52 would be moved to its lower position in order to havethe A street red signal go out during the amber period. Switch 64 would also be closed.

To obtain the following sequence,

Peiiiod Period 2 Persiod Period 4 Peiiiod Street A Green. Green-Am- Red... Red Green.

er. Street B Red-.. Red GI'GBIL Green-Am- Red.

of switches 48, 52, 56, BI and as.

The special tap #67 on the transformer T is to provide suitable reduced voltage to operate relays 6 and l in series with their condensers 33 and 22 respectively. Resistances could be used in place of condensers 33 and 22 in which case tap #67 could be transferred to the grounded side, of the transformer, connected with wire 12. In this case, if the voltage from the source of supply were satisfactory for the detector circuit transformer T-could. be omitted. Resistances 3| and 39 are introduced to limit the initial charging current to the condensers 33 and 22 when cam C2 en-' gages with contact In and cam C8 engages with contact [4.

The switch 14 is provided to permit the entire apparatus to be disconnected from the power supply.

The switch 18 is provided to permit the signals to be normally extinguished in the absence of tralfic when the apparatus is in the rest position if desired. This switch is shown in its normal position for the A green signal and the B red signal to be displayed in the rest position by connection of armature 40 directly to the positive power wire. If it is desired to have the signals normally extinguished switch 13 is moved into contact with wire 19 connected with-the motor M circuit so that armature 40 obtains positive power for control of the signals only when the motor has power, that is at all times except when the controller is actually stopped in the rest position of the cycle at the end of, the Astreet green period.

It will be noted from the cam diagram and a comparison of the several signal sequences that the cam contacts of the fixed time controller are closed to provide output power in four periods which may be identified as fixed time signal periods, A green, A amber, B green and B amber in sequence. Some fixed time controllers provide only three cam contacts and output power circuits, one for A green and B red, a second for B green and A red and a third for a common A and B amber energized in both the A and the B amber periods. 'Others separate the A and B amber circuits and have both green" and. red periods overlap the amber, and thus add one more cam contact and output power wire making four. Others also have the green signal period end at the beginning of the amber period but have the red on the opposite street overlap Y the amber periodas shown in the case of the six CamsCZ; C3, C4, C5, C6, C1 in the cam diagram. However in every case it will be observed that there are no ouput power circuits overlapping three periods in the controller cam contact cycle, whereas to provide for trafficactuated control two such threeperiod power circuits are needed, the first for energizing the motor M, independent of trafiic actuation, in the B green; '13 amber and'A "green periods, and the second for maintaining the detector relay '8 lock-in circuit-"(or both the lock-in and operating circuit as illustrated in the present embodiment) throughout the B amber, A green and A amber periods after any momentary operation of this relay by traflic' actuation in any of these three periods. Thereforeanimportant .feature of the present invention lies in providing relay means which will be,operated by the one;

period and two period power circuits of the controller cams and will combine certain of these periods into certain three, period new output power circuits from the relay c oritatcts of such additional cams for which there-'is ordinarily;

insufiicient room. Therefore the present invention in a novel manner makes use of the A amber period of the controller as a rest period to interrupt the motor and places the A green and A amber signals under the control of the output contacts of the relay means of the adaptor so that the A amber signal is kept disconnected and the A green maintained energized in the A amber period of the cam cycle when the controller is at rest and until traffic actuation operates a relay 8 to start the motor and reverse these signal connections so as to restore the usual A amber signal in the A amber period as a cycle of operation is started. The traific actuated relay 8 controls the motor in the A amber period of the cam cycle, and the relays 6 and I control the m0- tor in the other three periods.

It Will be appreciated that the detectors 23 are shown in the drawing as simple contact devices for simplicity of illustration and may in practice take any number of other forms.

Although green, amber and red trafiic signals are shown and described herein as these are most widely used in street trafilc signaling, there are some locations where only green and red signals are employed and a darkperiod or some form of overlap of the signals provided as a signal change period in place of the amber change period disclosed herein, and it will be appreciated that the invention is notlimited to the use of amber signals in the change period.

t will be further understood that the camshaft S and cams and cam contacts of the controller comprise a cyclic switching device and that such device may be in the form of a multiple contact drum or other well known forms providing a sequence of output power impulses such as illustrated in the cam diagram.

It will be appreciated by those skilled in the art that various other changes or substitutions may be made in the various parts of the apparatus or an arrangement thereof, without departing from the spirit of the invention as defined in the claims.

I claim:

1. In a trafiic control system for intersecting roads having a cyclic switching controller providing a plurality ,of switches and driving motor means therefor and having a plurality of switch positions through which it is operable by said motor means to provide a time cycle including in sequence a right of way signal period for the main road, a signal change period, a right of way signal period for the cross road, and a second signal change period, means to render said controller operable through said signal cycle in response only to trafiic on the cross road, said means comprising means for detecting traffic in the cross'road, a relay connected to said trafiic detector means to be operated by actuation of the latter by traffic, relay means connected to certain of said switches to be operated thereby in said sequence of periods and having output relay contacts to interrupt said motor in the first said change period and to operate said motor in the other three periods, and contacts operated by the first mentioned relay when actuated to operate said motor, a lock-in circuit for said first relay to maintain this relay operated after detector actuation and including contacts operated by said relay means to interrupt the lock-in circuit in the cross road right of way period and to maintain the lock-in circuit throughout the other three periods after detector actuation.

2; In a traflic control system for intersecting roads having a cyclic switching controller providing a plurality of switches and driving motor means therefor and having a plurality of switchpositions through which it is operable by said motor means to provide a time cycle including in sequence a right of way signal period for the main road, a signal change period, a right of way signal period for the cross road, and a second signal change period, means to render said controller operable through said signal cycle in response only to traific on the cross road, said means comprising means for detecting traflic in the cross road, a relay connected to said traflic detector means to be operated by actuation of the latter by traflic, relay means connected to certain of said switches to be operated thereby in said sequence of periods and having output relay contacts to interrupt said motor in the first said change period and to operate said motor in the other three periods, said contacts operated by the first mentioned relay when actuated to operate said motor, a lock-in circuit for said first relay to maintain this relay operated after detector actuation and including contacts operated by said relay means to interrupt the lock-in circuit in the cross road right of way period and to maintain the lock-in circuit throughout the other three periods after detector actuation, additional contacts operated by said first relay in absence of actuation to energize the main road right of way signal and interrupt the first change signal in said first change period and upon actuation to interrupt said main right of way signal and to energize said first change signal in said first change period.

3. In a traffic control system for intersecting roads having a cyclic switching controller providing a plurality of switches and driving motor means therefor and having a plurality of switch positions through which it is operable by said motor means to provide a time cycle including in sequence a right of way signal period for the main road, a signal change period, a right of way signal period for the cross road, and a second signal change period, means to render said controller operable through said signal'cycle in response only to traffic on the cross road, said means comprising means for detecting traffic in the cross road, a relay connected to said trafiic detector means to be operated by actuation of the latter by trafiic, relay means connected to certain of said switches to be operated thereby in said sequence of periods and having output relay contacts to interrupt said motor in the first said change period and to operate said motor in the other three periods, said contacts operated by the first mentioned relay when actuated to operate said motor, a holding device for said first relay to maintain this relay operated after detector actuation and including contacts operated by said relay means to interrupt the holding device in the cross road right of way period and to maintain the holding device operative throughout the other three periods after detector actuation, additional contacts operated by said first relay in absence of actuation to energize the main road right of Way signal and interrupt the first change signal in said first change period and upon actuation" to interrupt said main right of way signal and to energize said first change signal in said first change period.

4. In a trafiic control system for intersecting roads having a cyclic switching controllerproviding a plurality of switches and driving motor means therefor and having a plurality of switch positions through which it is operable by'said motor means to provide a time cycle including in sequence a right of way signal period for the main road, a signal change period, a right of way signal period for the cross road, and a second signal change period, means to render said controller operable through said signal cycle in response only to traffic on the cross road, said means comprising relay means for actuation by trafiic in the cross road to operate said motor and further relay means operated by said switches to combine the second change period and main right of way period and first change period into one output period for operation of the trafiic actuated relay means in said three periods after initial actuation by trafiic, and to combine the cross right of way period and second change period and main right of way period into another output period for operation of said motor through the remainder of one'complete cycle after initial operation by said traffic actuated relay means.

5. In a traffic control system for intersecting roads having a cyclic switching controller pro- 7 viding a plurality of switches and driving motor means therefor and having a plurality of switch positions through which it is operable by said motor means to provide a time cycle including in sequence a right of way signal period for the main road, a signal change period, a right of way signal period for the cross road, and a second signal change period, means to render said controller operable through said signal cycle in response only to trafiic on the cross road, said means comprising relay means for actuation by traflic in the cross road to operate said trafiic actuated relay means and contact means operated by said traffic actuated relay means in absence of actuation to energize the main road right of way signal and interrupt the first change signal in said first change period and upon actuation to interrupt said main right of way signal and to energize said first change signal in said first change period.

6. Trafiic control apparatus for converting a fixed time cyclic right of way signal control system having a time cycle including four periods into a traffic actuated right of way signal control system, comprising a trafiic detector device, a relay having an operating circuit connected with said device to be operated by trafiic actuation ofthe latter and having a lock-in circuit to mlaintain the relay operated after such actuation, relay means having input operating circuits for individual operation in certain of the four periods of the time cycle and having an output circuit providing output power overlapping three of said four periods, and a connection betwen said output circuit and the lockin circuit of the traific actuated relay to maintain the lock-in circuit effective throughout said fourth period.

three periods and interrupt the same in the '7. Traffic control apparatus for converting a fixed time cyclic motor operated right of waysignal control system having a time cycle including four periods into a trafiic actuated right of way signal control system, comprising a traific detector device, a relay having an operating circuit connected with said device to be operated by traffic actuation of the latterand having a lock-in circuit to maintain the relay operated after such actuation, relay means having input-operating circuits for individual operation in certain of the four periods of the time cycle and having an output circuit providing output power overlapping three of said four periods, and a connection between said output circuit and the lock-in circuit of the traffic actuated relay to maintain the lock-in circuit effective throughout said three periods and interrupt the samein the fourth period, another three period output circuit from said relay means to operate said motor in the latter three periods and interrupt the motor to stop cyclic operation in a different fourth period of the cycle, and an output circuit. from said traffic actuated relay to operate said motor when said traflic actuated relay is operated.

-8. Traflic control apparatus for converting a fixed time cyclic motor operated right of way signal control system having a time cycle including 'four periods into a traflic actuated rightof way signal control system,comprising a trafiic detector device, a relay having an operating circuit connected with said device to be operated by traffic actuation of the latter and having a. lockin circuit to maintain the relay operated after such actuation, a second relay having an'operating input'circuit for energization in-the-second of the-four periods of the time cycle and a lock-in circuit to maintain it operated in the second and third periods and having another input-circuit to short circuit said second relay in the fourth period to deener-gize said second relay in the fourth and first periods, a third relay having an operating input circuit forenergization in; the third period of the cycle and a lock-in circuit to maintain it operated in thethird and fourth periods and having another input circuitto short circuit said thirdrelay to deenergize the same in the first and second periods, contacts operated by the respective relays, an output circuit including contacts closed by said second and third re-- layswhen either one is deenergized and con-- nected to the lock-in circuit of said first relay to render the latter eifective in said second, fourth and first periods and interrupt the latter in said third;period,- a second output circuit including" contacts operated by said second and third relays when the second relay is deenergized and" also when the third relay is energized to provide outputpoweroverlapping said third, fourth and first periods for operation of said motor in these periods and interruption of the motor in said second period, and an output circuit including contacts closed by operation of said first relayto trafiic actuated right of way signal control; systern; comprising'means to detect the presence of;- cross trafiic, a relay having an operating ,circuit connectedwith said device to be operated by traffic-actuation of the latter and having a lockin circuit tomaintain the relay operated after such actuation, a second relay having an operating-input; circuit for energization in the main change period and a lock-in circuit to maintain it operated in said main change period and the following cross right of way period and having another input circuit to short circuit said second relay in said cross change period to deenergize said second relay in said cross change period and, the following main right of way period, a third relay having an operating input circuit for energization in the cross right of way period and having another input circuit to short circuit said third relay in said main right of way period to deenergize the saine in said main right of way period and the following main change period, contacts operated by the respective relays, an output circuitincluding contacts closed by said second and third .relayswhen either one is deenergized and connected to the lock-in circuit of said first relay to render'the latter effective in said cross change, said, main right of Way, and said main change periods and to interrupt the latter in said cross right of way period, a second output circuit including contacts operated by said second and third relays when the second relay is deenergized andalso when the third relay is energized to provide output power overlapping said cross right of way, said cross change and said main right of way periods for energization of the motor in the last'mentioned three periods and interruptionpf the motor in said main change period, and anoutput circuit including contacts closed by operation of said first relay to operate said motor when said first relayflis operated.

10. Trafilc control apparatus as in claim 9 in. which a signal power output circuit for the main right of, Way signal is provided through contacts on said relays from a connection with the operating circuit of said motor whereby the signals will be deenergized normally in the main change period when the motoris interrupted by absence of tr-afiic actuation.

V11. Traflic control apparatus for converting a fixed time cyclic motor operated right of way signal control system, having a power output cycle including a main right of way period, a mainchange. period, a cross right of way, and a cross change period in the sequence stated, into a trailic actuated right of way signal control system comprising means to detect the presence of cross trafiic, a relay having an operating circuit com'iected with said means to be operated by trafii'c actuation of the latter and having a lockin circuit to maintain the relay operated after such actuation, a second relay having an operat ing input circuit for energization in the main change period and a lock-incircuit to maintain it operated in said main change period and the following cross right of way period and having another input circuit to'short circuit said second relay insaid cross change period to deenergize said second relay in said cross change period and the" following .main right of way period, a third relay having an operating input circuit for energizationin the cross right of way period and having another input circuit to short circuit said outputcircuit including contacts closed by said ,secondandthird relays when'either one-is deenacce e? "ergized and connected to the lock-in circuit of said first'relay to render the latter effective in said cross change, .said main right of way, and said 'main change periods and to interrupt the latter in said cross right "of way period, a second output circuit including contacts operated by said second and third *relays'when the second relay is deenergized and also when the third relay is energized to provide output power overlapping said cross right of way, said cross change and said main right of way periods for energization of the motor in the last mentioned three periods and interruption of .the motor in .said main change period, and an output circuit including contacts closed by operation of said first relay to operate said motor when said first relay is operated, a third output circuit including contacts closed by said third and first relays when both are .deenergize-d to supply power for energization of the main right of way' signal in the main change period in absence of traific actuation, a fourth output circuit including contacts closed by all three said relays when said first and second relays are energized and said third relay is deenergized to supply power for energization of the main change signal in the main change period upon trafiic actuation, and additional output circuits including contacts operated by said second and third relays to provide output power for energization of the main right of way, cross right of way and cross change signals in their respective periods whereby said signals will be energized continuously throughout their respective periods despite any momentary interruptions of the power output from the switches of said cyclic controller during such respective periods.

12. Traffic control apparatus for converting a fixed time cyclic motor operated right of way signal control system, having a power output cycle including a main right of way period, a main change period, a cross right of way, and a cross change period in the sequence stated, into a trafiic actuated right of way signal control system, comprising means to detect the presence of cross traffic, a relay having an operating cir- L ating input circuit for energization in the main change period and a lock-in circuit to maintain it operated in said main change period and the following cross right of way period and having another input circuit to short circuit said second relay in said cross change period to deenergize said second relay in said cross change period and the following main right of way period, a third relay having an operating input circuit for energization in the cross right of way period and having another input circuit to short circuit said third relay in said main right of way period to deenergize the same in said main right of way period and the following main change period, contacts operated by the respective relays, an output circuit including contacts closed by said second and third relays when either one is deenergized and connected to the lock-in circuit of said first relay to render the latter eifect'ive in said cross change, said main right of way, and said main change periods and to interrupt the latter in said cross right of way period, a second output circuit including contacts operated by said second and third relays when the second relay is deenergized and also when the third relay is energized to provide output power overlapping said crossright of way, said cross-change and said main right of way periods forenergization of the motor in the last mentioned three periods and interruption of the. motor in .said main change period, and an output circuit including contacts closedby operation ofsaid first relay to operate said motor when said first relay is operated, a third output circuit including contacts closed by said "third and first relayswhen both are deenergized to supply power for energiza-tion of the main right of way signal in the main change period in absence of trams actuation, a fourth output circuit including contacts closed by all three said relays when saidfirst and second relaysare energized and said third relay is deenergized to supply power for energization of the main change signal in the main change period upon traffic actuation. 1

13. 'Trafiic control apparatus as in claim 12 in which the output power circuit for energization of the main right of way signal through the relay contacts as aforesaid is connected forpower source only to the operating circuit of said motor whereby the signals will be deenergized normally in the main change period when the motor is interrupted by absence of trafiic actuation.

l4. Trafiic control apparatus for converting a fixed time cyclic signal controller having "a four period cycle with power output individual to one period and two periods only of said four periods into a controller adapted to have its signal cycle initiated by trafic actuation, said apparatus comprising relay means having power input operating circuits for energization of the relay means in one period and for short circuit of the relay means for deenergization in a subsequent period, and power output circuits including contacts operated by said relay means to energize said output circuits during three of said four periods.

15. Traffic control apparatus for connection to a cyclic signal controller having a four period time cycle and power output circuits energized individually in single periods of said cycle, said apparatus comprising relay means having input operating circuits for connection to certain of said power output circuits for operation of said relay means individually in said periods and having other output circuits including contacts operated by said relay means and combined to provide output power overlapping three of said four periods.

16. Trafiic control apparatus for connection to a cyclic signal controller having a four period time cycle and one power output circuit energized in the first of said fourperiods, a second output circuit energized in the third of said periods, and a third output circuit energized in the second and fourth of said periods, said apparatus comprising relay means having input operating circuits for connection to certain of said output circuits and having other output circuits including contacts operated by said relay means and combined to provide output power overlapping the third and fourth and first periods on one of thelast named circuits and overlapping the fourth, first and second periods on another of said last named circuits.

1']. Traffic control apparatus for connection to a cyclic signal controller having a four period time cycle and power output circuits energized individually in single periods of said cycle, said apparatus comprising relay means having coils and contacts operated thereby, input operating circuits for said coils for connection to certain of said power output circuits for operation ofsaid coils individually in certain of said periods, and further output circuits including said contacts and connected together to provide output power overlapping three of said four periods.

18. Traific control apparatus for converting a fixed time cyclic signal controller having a four period cycle with power output individual to one period and two periods only of said four periods into a controller adapted to have its signal cycle initiated by trafiic actuation, said apparatus comprising relay means having power input operating circuits for energization of the relay means in one period and for short circuit of the relay means for deenergization in a subsequent period, and power output circuits including contacts operated by said relay means to energize said output circuits during three of said four periods, traffic actuated relay means having a stick circuit connected to one of said three period power output circuits for maintaining said traflic actuated relay means in actuated condition throughout said three periods after momentary trafiic actuation therein and for releasing said traffic actuated relay means from actuated condition in said fourth period.

19. Traffic control apparatus for converting a fixed time cyclic signal controller having a four period cycle with power output individual to one period and two periods only of said four periods into a. controller adapted to have its signal cycle initiated by trafiic actuation, said apparatus comprising relay means having power input operating circuits for energization of the relay means in one period and for short circuit of the relay means for deenergization in a subsequent period, and power output circuits including contacts operated by said relay means to energize said output circuits during three of said four periods, trafiic actuated relay means having a stick circuit connected to one of said three period power output circuits for maintaining said traflic actuated relay means in actuated condition throughout said three periods after momentary traific actuation therein and for releasing said traflic actuated relay means from actuated condition in said fourth period, said controller having a motor for driving the controller through its cycle, and said apparatus including an operating connection for said motor to another of the said three period output circuits for operation of said motor during only the latter three periods, and another operating connection for said motor from said traffic actuated relay means for operation of said motor when the latter relay means is in actuated condition.

JOHN L. BARKER. 

